Turning 13 is a major milestone for a young girl. If your daughter or someone close to you is celebrating a 13th birthday, make a cake that is fitting of a girl's entry into her teen years. Look at the types of things that young girls like as well as the theme of the party and incorporate those into the decoration or the shape of the cake.
Place your 9-inch round cake on the centre of a cake platter and frost it with frosting in the colour of your choice. Choose a colour that the girl likes or a colour that coordinates with the decorations you are using at the party.
Place the 8-inch round cake on top of the 9-inch cake. Frost it with the frosting as well.
Choose pre-made fondant in a colour that contrasts, but coordinates, with the frosting you chose. Roll out the fondant with your rolling pin to about a 1/8-inch thickness.
Cut polka dot shapes out of the fondant with a small, round cookie cutter.
Lightly press the polka dots against the cake so that they stick to the frosting. Create a random pattern with the polka dots and put as many or as few as you would like.
Place your rectangular cake on the centre of a cake platter. Frost the cake with white icing.
Place black frosting inside a pastry bag and use it to pipe the outline of the features of her mp3 player onto the cake. For example, if she has an iPod, pipe a large rectangle onto the top half of the cake and a large circle on the bottom half.
Fill the pastry bag with pale blue frosting. Use the pale blue frosting to fill in the screen of the mp3 player and the specific controls on the mp3 player.
Pipe a birthday message onto the screen of the mp3 player using either the black or white frosting.